Is it possible to Link one or more layers from another .blend file?
It will be easier to do that the other way around - link objects from the original scene into new one within one blend file.



In that case you have the freedom to select objects as you wish, including selecting objects by 3D layer, selecting all the children of the parent or vice versa via Select Grouped menu and so on.

Once objects are selected, in Object mode press Ctrl+L > Objects To Scene (additional scene should be already created). You can either render from that additional scene or link/append the scene into another blend via Append or Link and choosing Scene.